This invention relates generally to semiconductor chip device packages and assembly. More specifically, the invention relates to an interposer tape for a tape ball grid array package which permits varying sized dies to be used for the same package.
In semiconductor design and assembly, an integrated circuit chip or xe2x80x9cdiexe2x80x9d may be bonded to a tape substrate before connection to a board. FIG. 1A illustrates a conventional tape ball grid array (TBGA) package 100. The conventional TBGA package 100 has a die 102 mounted upon a tape 104. The tape 104 includes bond fingers 106 for wire bonding to bond pads 107 of the die 102. The bond fingers 106 are connected to ball attach sites 108 via connecting metal traces 110 (FIG. 1B). The ball attach sites 108 coincide with holes 112 which are used for attaching solder balls to the conventional TBGA package 100. The solder balls permit external communication, i.e. to a mother board.
Often, it is desirable to change the size of the die 102 for the conventional TBGA package 100. For the tape 104, the size of the die 102 is limited to a range of sizes. For smaller dies, this limitation is determined by the length of bond wires 112 which extend from the die 102 to the bond fingers 106. More specifically, during injection of an encapsulating plastic, long bond wires 112 are likely to bend, contact each other and short out. This phenomenon is known as xe2x80x9csweepxe2x80x9d and limits the length of bond wires 112. As a result, to substantially decrease the size of the die 102, a new tape 104 is typically required.
The metal traces 110, the bond fingers 106 and the ball attach sites 108 form an interconnect pattern 111 as illustrated in FIG. 1B. In the past, to overcome sweep and permit a smaller die 102, designers have opted to alter the interconnect pattern 111. One. interconnect pattern 111 approach has been to move the bond fingers 106 towards the die 102. However, this solution is limited by the width of the metal traces 110 and the. density of the interconnect pattern 111. More specifically, conventional routing limitations dictate that a maximum of three or less metal traces 110 may be placed between two adjacent ball attach sites 108. More than three metal traces 110 placed between two adjacent ball attach sites 108 may compromise the mechanical strength and manufacturability of the tape 104. As a result, the bond fingers 106 may not extend close enough to the die 102 to allow manageable wire bond lengths to connect to the bond pads 107. Correspondingly, the size of the die 102 remains limited for the tape 104.
Thus, the length of the wire bonds 112 and the interconnect pattern 111 limit the size of the die 102 which can be used for the tape 104. If the die 102 size is changed, such that it is outside the range of the bond wires 112, a new tape must be designed and manufactured. As a result, this requires the design of multiple tapes for different die sizes. Each new tape increases cost and time consumption in design and manufacturing. In addition, it also quite common that different size dies also change the interconnect pattern 111, which necessitates a new tape and increases costs for the package 100. Further, in some cases, the allowable wire length for the wire bonds 112 and interconnect pattern 111 routability may limit the minimum size of the die 102.
In view of the foregoing, a package which may accommodate multiple die sizes and small die sizes would be desirable.
To achieve the foregoing, the present invention provides an interposer tape which provides electrical communication between a die and a packaging substrate. The interposer tape permits multiple die sizes to be used for the substrate. More specifically, the dimensions of the interposer tape may vary to accommodate a variety of die sizes for the substrate. The interposer tape includes an array of traces. The array of traces provide electrical communication between bond pads of the die and bond fingers of the substrate. A first set of wire bonds may be formed between the array of traces and the bond pads of the die. A second set of wire bonds may be formed between the array of traces and the bond fingers of the substrate.
In one aspect, the invention provides a semiconductor package. The semiconductor package includes a packaging substrate. The semiconductor package also includes an interposer tape mechanically bound to the packaging substrate and in electrical communication with the packaging substrate. The semiconductor package further includes a die mechanically bound to the substrate and in electrical communication with the interposer tape, wherein the interposer tape provides electrical communication between the substrate and the die.
In another aspect, the invention relates to an interface between a die and a packaging substrate. The interface includes an interface substrate. The interface also includes an array of conductive links, wherein the array of conductive links are adapted to fitting a plurality of die sizes to the packaging substrate.
In yet another aspect, the invention provides a method of fabricating a semiconductor package. The method includes providing a packaging substrate. The method also includes mechanically binding an interposer tape to the substrate, the interposer tape including an array of conductive links. The method further includes mechanically binding a die to the substrate. The method additionally includes forming a first set of wire bonds between the interposer tape and the die. The method also includes forming a second set of wire bonds between the interposer tape and the substrate.
These and other features and advantages of the present invention are described below with reference to the drawings.